The phrase "when asserting" is correct and usable in written English.
It can be used when discussing the act of stating or declaring something confidently or forcefully.
Example: "When asserting your opinion, it's important to provide evidence to support your claims."
Alternatives: "when stating" or "when declaring".
Mr Jacobson is best when asserting the merits of a smart comic novel.
When asserting theft, the aggrieved builder can point to them as proof.
When asserting this defense, the member shall include evidence of the amount of the judgment that has been satisfied.
Mr. Bagley laid out one of his grammatical pet peeves: the use of the preposition "of" along with an apostrophe-S when asserting possession.
It is silliest when asserting that "by imagining themselves into the body of Sasquatch, white working-class men could imagine themselves as black, as women, could come in contact with their own souls".
Mr. Santorum is the only one of the three who can actually appear heartfelt when asserting, as he did today on Morning Joe, that "the central issue of the day is government oppressing and taking away our economic freedoms".
The fascinating efforts of Anonymous can be messy, but so are many freedoms when asserted so boldly.
"The question is not whether there will be a transition to flat panel, but when," asserts Chris Zagorski, manager of peripherals marketing for Dell.
Dually, par will generate a splitting when asserted by the Opponent, thus the particle rule will let the defender choose the context.
Knowing when to assert themselves and when to let art speak for itself was part of the answer.
"In that sense, Rick chooses very carefully when to present himself, when to express his views, when to assert himself".
